Horse Grass Allergies

Written by karin barga Google
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Horse Grass Allergies
Grass allergies often present as boils on the horse's skin. (horse image by Natalia Solovyeva from

All living creatures are capable of forming allergies, though some species are more challenging to diagnose than others. Responsible horse owners will recognise changes in their animals' behaviour or appearance. These noticeable changes can indicate either an allergic reaction or other common equine health conditions. It is up to the animal's veterinarian to diagnose allergies.

Allergy Symptoms

Horses can exhibit numerous symptoms when suffering from allergies. The most common symptoms are tearing eyes, coughing and raised bumps around the withers. Physical symptoms may not exist at all, and an owner may simply notice a horse does not look well. Attentive, responsible owners are typically able to notice immediately when their horse is displaying a change in behaviour, mood and activity.

Diagnosing Allergies

Veterinarians often recommend horse owners inquire about past allergies and outbreaks prior to purchasing a horse. Previous allergic reactions should not prevent the purchase of a new horse, but instead will provide a medical history of symptoms and reactions, leading to quicker and more effective treatment.

Equine allergies can take weeks, months or years to develop fully. Just as with humans, a horse can develop allergies suddenly and without warning. Because there are so many environmental allergens a horse is exposed to, it is difficult to initially diagnose allergies. Any horse can develop hives or skin allergies at any time, regardless of age, gender or breed.


Under normal living conditions, dust, mould spores and other allergens surround horses on a daily basis. There are proteins found in grazing pastures that could potentially cause allergic reactions. In most circumstances, a healthy horse's immune system can fight off such allergens, but this is not always the case. Proteins produced by a healthy horse's immune system, called antibodies, are the horse's weapon against allergens. Hypersensitivity, or allergic reactions, occur when the immune system overreacts to an allergen. Anything in the air is a potential allergen, such as mould, dust or spores. Certain foods, hay, grass, supplements, grains and insects can also trigger allergic reactions.

Grass Allergies

Grass allergies in horses are rare, but certainly not unheard-of. Horses may develop an allergy to a particular strain of grass; however, an allergic horse is not usually allergic to all grass. In one particular case near London, an owner became very concerned when her 5-year-old mare developed large boils and breathing problems after simply touching the grass.

"During the summer she has to come in and stay in through the day, which also means she can't be ridden," the horse's owner reported. The horse now wears a polyester-based, breathable coat and protective mask when turned out. She eats a sugar beet chuff and soy oil mixture with her daily dose of antihistamine tablets.

Allergy Testing

The veterinarian draws a small amount of blood and submits the sample to a laboratory for allergy testing. The allergy test administered detects elevated levels of antibodies for specific allergens causing the horse's symptoms. The allergy panel tests for numerous individual allergens, including grass pollens, moulds, insects and trees.

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